青鳉与食蚊鱼竞争排斥的生态形态学解释

Ecomorphological traits explaining the competition exclusion between Oryzias and mosqui-tofish

生态形态学理论指出,形态相似的物种生态位相似,是导致种间竞争排斥的关键性因素。在鱼类入侵生态学研究中引入生态形态学理论,对于加深理解入侵种与土著种的种间相互关系有着重要意义。本文利用形态分析方法,对广东怀集燕都国家湿地公园入侵种食蚊鱼对土著种鳍斑青鳉和弓背青鳉的影响机制进行研究。结果表明:弓背青鳉和鳍斑青鳉在研究区域常同域分布,但两者的空间分布格局差异显著。两者形态高度相似,符合生态形态学"形态相似者竞争排斥"理论。与群落其他鱼类相比,食蚊鱼与2种青鳉鱼类形态更为相似。聚类分析发现,食蚊鱼和青鳉鱼类聚合在同一分枝,且其空间生态位的重叠度极低。种群相对密度调查显示,食蚊鱼与青鳉鱼类种群数量呈显著的负相关关系。食蚊鱼的入侵是导致2种青鳉鱼类种群数量明显下降的关键原因。形态特征的相似性能够初步解释食蚊鱼与青鳉鱼类的竞争排斥关系,尚需从不同角度就食蚊鱼入侵对青鳉鱼类的作用机制进行深入探索。

The theory of ecomorphology predicts that species with similar morphological traits can occupy similar ecological niche,which may cause competitive exclusion.To apply this theory into fish invasion ecology research is of significance for understanding the interaction between native and invasive species.Here,we compared the morphological difference between two native(Oryzias pectoralis,Oryzias curvinotus)and one invasive species(Gambusia affinis)to explore the competitive exclusion among them.The results showed that despite O.pectoralis and O.curvinotus were sympa-tric species,they varied in spatial distribution.Such a result supported the theory of ecomorphology,which predicts that two species with similar morphological traits might have strong competition.Moreover,their population density exhibited a significant negative relationship with that of G.affinis.The morphology of G.affinis and both Oryzias species were more similar when comparing to other fish in the assemblage.Results from the cluster analysis showed that G.affinis and Oryzias species were close in a branch,with extremely low spatial niche overlap between invasive mosquitofish and native Oryzias species.There was significant negative correlation between the population abundance of mosquitofish and Oryzias species.All the results suggested that mosquitofish led to population decline of both Oryzias species,due to the ecomorphological similarity.More studies are needed to better understand the mechanisms of G.affinis invasion in habitats of native Oryzias species.